CVE-2001-1251 in Small HTTP Server
Summary
by MITRE
SmallHTTP 1.204 through 3.00 beta 8 allows remote attackers to cause a denial of service via multiple long URL requests.
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Analysis
by VulDB Data Team • 04/08/2019
The vulnerability identified as CVE-2001-1251 affects SmallHTTP server versions 1.204 through 3.00 beta 8, representing a denial of service weakness that can be exploited by remote attackers. This issue stems from the server's inadequate handling of malformed or excessively long URL requests, creating a scenario where malicious actors can overwhelm the system's resources and render it unavailable to legitimate users. The vulnerability specifically targets the HTTP request processing mechanism within the SmallHTTP server implementation, where the software fails to properly validate or limit the length of incoming Uniform Resource Locator requests.
The technical flaw manifests when the server receives multiple consecutive requests containing unusually long URLs that exceed normal processing limits. This condition triggers a resource exhaustion scenario where the server's memory allocation and processing capabilities become overwhelmed, leading to system instability and eventual service disruption. The vulnerability operates at the application layer of the network stack, classified under CWE-400 as an unchecked resource allocation issue, where the server does not adequately enforce bounds checking on incoming request parameters. Attackers can exploit this weakness by crafting specially formatted HTTP requests with URLs that contain excessive character sequences, typically exceeding normal URL length constraints.
The operational impact of this vulnerability extends beyond simple service interruption, as it can be leveraged to create sustained denial of service conditions that significantly affect system availability and user access. Organizations relying on SmallHTTP server implementations within their infrastructure face potential business disruption when this vulnerability is exploited, particularly in environments where continuous service availability is critical. The attack vector requires no authentication or specialized privileges, making it accessible to any remote attacker with basic network connectivity to the affected server. This characteristic aligns with ATT&CK technique T1499.004, which describes network denial of service attacks targeting application layer protocols.
Mitigation strategies for CVE-2001-1251 should focus on implementing proper input validation and request length limiting mechanisms within the SmallHTTP server configuration. System administrators should consider upgrading to patched versions of the SmallHTTP server software, as the vulnerability was addressed in subsequent releases. Additionally, implementing rate limiting controls and request size restrictions at network level firewalls or load balancers can provide additional protection against exploitation attempts. The vulnerability demonstrates the importance of proper resource management and input validation in web server implementations, emphasizing that even seemingly benign features like URL handling can become attack vectors when not properly constrained. Organizations should also implement monitoring solutions to detect unusual patterns of long URL requests that could indicate exploitation attempts, enabling proactive response to potential attacks.